it is not ok. but it depends the way u updated ur phone to nougat. I did OTA and it has minor bugs because the cache of the previous marshmellow 6.0 is not fully cleared and also keep in mind that we are on January security patch and no major update rolled out since. but if you updated to nougat by resetting your phone or did a factory reset. you should be fine. overall all I am experincing is minor lags. but as you said if ur battery drains fast you should clear the cache and try it. if not do a reset, and if reset doesn't fix ur problem send it to Samsung if your warranty is still valid.
